BRUCK FAQ
Operating devices
1. What types of transformers are there and how do they differ?
Toroidal Transformers
Toroidal transformers are the most efficient magnetic transformers. Depending on the quality of the copper wire, the efficiency is between 75–85%. Due to their closed, air-gap-free toroidal design, no-load losses are significantly lower than those of EI-core transformers. Toroidal transformers are suitable for applications where low standby losses are important. By oversizing the transformer, losses under load can also be reduced: at 50% partial load, losses are only ¼ of those at full load.
BRUCK toroidal transformers feature short-circuit protection via a fuse, as well as overload and overtemperature protection. A current monitor according to VdS / ENEC can optionally be connected. With BRUCK toroidal transformers, you can be on the safe side.
EI-Core Transformers
EI-core transformers, also called "block transformers", have primary and secondary windings wound separately next to each other on the core. Due to the longer magnetic path through air, losses are higher than with toroidal transformers. Efficiency ranges from 70–80%. BRUCK EI-core transformers have short-circuit protection via a fuse, as well as overload and overtemperature protection. A current monitor according to VdS / ENEC can optionally be connected. With BRUCK EI-core transformers, you are on the safe side.
Electronic Transformers with AC Secondary Output
Electronic transformers (AC) are very compact. Their small size makes them ideal for use in luminaires or for ceiling/wall installation. The primary voltage is converted to secondary voltage via a combination of small coils and electronic components, allowing high efficiency of 95–98%. The AC secondary voltage operates at 40–50 kHz, which usually limits the secondary cable length to around 2 meters. Please also refer to the manufacturer’s individual specifications.
BRUCK AC electronic transformers provide maximum safety and convenience with short-circuit, overload, and overtemperature protection. After a fault is corrected, they immediately return to full functionality. Soft start increases lamp life and reduces maintenance costs.
Electronic transformers require a minimum load of around 20%. If the minimum load is not reached, connected lamps may not light or may flicker. The transformer may also hum.
Electronic Transformers with DC Secondary Output
Electronic DC transformers differ from AC transformers mainly in having a rectified secondary voltage. This allows longer low-voltage systems to be powered. Depending on the transformer type, 6–20 meters of secondary cable are possible, allowing installation out of sight. DC transformers have an efficiency of 90–95%.
The minimum load of around 20% is also required, as with AC electronic transformers. If the minimum load is not reached, connected lamps will not light or may flicker, and the transformer may hum.
BRUCK DC electronic transformers provide maximum safety and convenience with short-circuit, overload, and overtemperature protection. After a fault, they immediately return to full functionality by switching the mains power off and on. Soft start increases lamp life and reduces maintenance costs.
2. How are transformers dimmed?
Dimming a halogen or incandescent lamp can significantly increase its lifespan and reduce energy consumption. Brightness decreases more than energy use when dimmed, which reduces energy efficiency. Frequently operating a lamp in dimmed mode can save energy by using a lower-wattage lamp. Dimming also changes the light color, increasing the red component.
3. Can multiple transformers be connected together?
Connecting Magnetic Transformers
When switching on magnetic transformers, the higher inrush current can trip the upstream circuit breaker. Inrush current can be up to ten times the nominal current. For example, a 300 VA transformer with 1.3 A nominal current may briefly draw up to 13 A. Using a 16 A circuit breaker can cause unwanted trips. Inrush current limiters prevent this. BRUCK magnetic transformers of 300 and 400 VA are equipped with inrush current limiters as standard, allowing multiple transformers to be connected.
Connecting Electronic Transformers
Multiple electronic transformers can be switched together with one switch without issues, as their inrush currents are low. Please note the switch’s rated load. High inrush spikes, as with magnetic transformers without inrush limiters, do not occur with BRUCK electronic transformers.
Electronic transformers must not be connected together on the secondary side.
4. Why do transformers sometimes hum?
Transformers usually consist of two coils wound around an iron core. The core is made of thin, insulated sheets. Humming occurs when magnetic forces cause the sheets to vibrate.
Electronic transformers work on a different principle and therefore do not hum. Here you can find solutions for silent operation of transformers.